Apparatus for converting rotational displacement into linear displacement

ABSTRACT

Apparatus for converting rotational displacement into linear displacement comprising a rotatable member and two sets of stationary members bearing each against one surface of said rotatable member. The rotatable member has two surfaces comprising a plurality of alternating oppositely inclined surfaces joined together to form a plurality of apices and the sets of stationary surfaces comprise posts adapted to register with one pair of oppositely inclined surfaces and one apex. For a given rotational displacement the posts contact at the same height of the inclined surfaces and the inclined surfaces are inclined in the same direction. This apparatus is useful as a means for actuating a timer to supply electrical power for a time interval while preventing accidental interruption of electrical power during the time interval.

United States Patent H51 3,699,291 Danti et al. 1 Oct. 17, 1972 APPARATUS FOR CONVERTING 3,032,618 5/1962 Johnson ..200/153 X ROTATIONAL DISPLACEMENT INTO 3,443,446 5/1969 Buergel ..74/56 LINEAR DISPLACEMENT Inventors: Bernard R. Danti, Lexington; Paul E. Brefka, Southboro, both of Mass.

Assignee: Millipore Mass.

Filed: April 1, 1971 Appl. No.: 130,193

Corporation, Bedford,

References Cited UNITED STATES PATENTS 11/1960 Metzner ..74/56 3/1968 Greven ..74/56 10/1950 Ambrose ..200/153 L 7/1965 Cope ..200/166 SD 9/1946 Hoover .,74/56 UX Apparatus for converting rotational displacement into Primary Examiner-Robert K. Schaefer Assistant Examiner-Robert A. Vanderhye AttorneyClarence S. Lyon ABSTRACT linear displacement comprising a rotatable member and two sets of stationary members bearing each,

against one surface of said rotatable member. The rotatable member has. two surfaces comprising a plurality of alternating oppositely inclined surfaces joined together to form a plurality of apices and the sets of stationary surfaces comprise posts adapted to register with one pair of oppositely inclined surfaces and one 12 Claims, 8 Drawing Figures PATENTEDnm 11 m2 sum 1 0r 3 Fig, 1

BERNARD R DA PAUL E. BREFKA PATENTEDBBI I 1 I912 3.699.291 SHEEI a or 3 2W 29 I MOTOR l 25 I I TIMER 26 L J I TEST ON RECTIFIER v 30 a FILTER TEST 18VDC Fig. Z. COMPLETE CELL IN\ 'EI\"I()R5 BERNARD R. DANTI P UL E. -BREFKA vl APPARATUS FOR CONVERTING ROTATIONAL DISPLACEMENT INTO LINEAR DISPLACEMENT This invention relates to an apparatus for supplying power at timed intervals and to an actuating control mechanism for use in such apparatus and others.

In some chemical analysis methods, it is necessary that the sample being tested be subjected to electrical current for precise periods of time to effect sample separation, with or without chemical reaction. For example, electrophoresis is a primary tool in analytic chemistry used to separate complex mixtures of molecules into their individual components. Electrophoretic analysis is based upon the fact that each molecule is characterized by a particular electrophoretic mobility under a given set of conditions. For example, most proteins exhibit a net negative charge which is enchanced in the alkaline pH range. When a mixture of materials is placed in a support medium, such'as a buffered gel, which is subjected to a voltage gradient, each material component of the mixture electrophoretically migrates through the support medium at its characteristic rate for that set of conditions. Electrophoretic mobility is a function of net charge, molecular weight and size and shape, and a number of other factors which can be controlled by the experimental conditions.

While electrophoretic migration of negatively charged molecules is occuring, another phenomenon, known as counterelectrophoresis, or endosmosis or electro-osmosis, also takes place. The positive ions in the buffer within the gel move toward the cathode. Polar water molecules, attracted to these positive ions, are swept along toward the cathode also. This flow of ions and water molecules toward the cathode tends to oppose the electrophoresis of negatively charged ions toward the anode. Endosmosis can be very useful, in that it washes weakly electronegative or electrically neutral molecules toward the cathode.

By making use of both electrophoresis and endosmosis which can cause molecule movement in opposite directions, one can cause a sample containing protein molecules to move toward a reagent containing neutral or weakly charged molecules so that they encounter each other within the gel. The sample and reagent can be positioned in the gel by placing them in wells formed by cutting out and removing a small section of gel, casting the gel around plugs which are subsequently removed or by other known means. When a particular component of the sample encounters the reagent, in the proper concentrations, a reaction occurs in the gel between the wells, such as a change in color or a precipitation.

The gel thickness and configuration are designed so that sample separation or reaction occurs after a time interval during whichthe gel is subjected to electrical current so that separation will occur prior to gel drying caused by the electrical current passing therethrough. Accordingly, it is essential that the power supply employed pass electrical currentthrough the gel continuously over a precise time period to permit visual observance of any positive reaction that may be effected. If current is passed through the gel for too short a time period, no reaction will occur because the reagent and sample will not have been contacted and thetechnician, not seeing any reaction, would conclude erroneously that the test was negative. On the other hand, if power is supplied for long a period, the sample may migrate into the reagent well resulting in no observable precipitation and/or color change. Again, the technician would conclude erroneously that the test was negative. Furthermore, if the power is not supplied continuously over the designed time, the same erroneous results may be obtained. In addition, it would be highly desirable to provide a power supply means which would prevent accidental interruption of the supplyv of electrical current to the gel.

The present invention provides a control means for converting rotational displacement into linear displacement. In one embodiment, the control means is employed with a timer and switching arrangement control the time period which electrical current is supplied to a set of electrical contacts. The control means comprises a rotatable member and two stationary members bearing each against one surface of the rotatable member to form two pairs of surfaces; each pair consisting of a rotatable surface and a stationary surface. One surface of each pair has a plurality of alternating oppositely inclined surfaces joined together to form a plurality of apices and the other surfaces of each pair comprising discrete spaced surfaces each adapted to register with one pair of oppositely inclined surfaces and one apex. Each pair of surfaces is arranged so that for a given rotational displacement the discretely spaced surfaces contact at the same height on the inclined surfaces and the inclined surfaces are inclined in the same direction. When the rotatable surface is rotated it moves linearly and the arrangement can be employed to contact a linearly-movable switching means which controls a timer.

The invention will be more fully described with reference to the accompanying drawings.

FIG. 1 is an exploded perspective view of a housing useful in electrophoresis containing the apparatus of this invention.

FIG. 2 is a schematic diagram of a circuit for controlling the power supply.

FIG. 3 is an exploded perspective view of the control means for activating or deactivating the power supply.

FIG. 4 is a top view of a control knob having a cam surface.

FIG. 5 is a bottom of the control knob of FIG. 3.

FIG. 6 is a plan view of the inside surface of the hood portion.

FIG. 7 is a rear view of a locking mechanism.

FIG. 8 is a side view of the locking mechanism.

Referring to FIG. 1, the power supply comprises a hood 1, a platform 2 and a base 3. The timer and control means are housed in the hood 1. The wiring and circuits needed to supply the desired power (not shown) are housed in the base 3. The platform 2 provides a convenient means for retaining a sample to be subjected to electrical current during operation of the test. A tray 4 which can be employed in conjunction with the power supply is described in detail in application Ser. No. 84,587 filed Oct. 28, 1970. The tray 4 is provided with a slot 5 which is adapted to be registered with a locking hook 6 located on the platform 2, and has electrodes 8 and 9 which contact electrical contacts 11 and 12. The means for operating locking means 7 will be described in detail below with reference to FlGS. 3, 7 and 8. The hoodl, platform 2 and base 3 are joined together by any convenient means as for example by screws as shown.

Referring to FIG. 2, to supply power for a timed interval to a sample being tested, switch is closed to activate a motor 21 in a timer 22. The timer 22 activates switch 23 so that it closes a circuit which includes a light 25 which indicates that the test is running. When the power is on, as controlled by the timer 22, AC current is converted to DC current by means of a rectifier and filter 26 so that DC current having the desired voltage is delivered to the electrophoretic cell 4. When the timer 22 has completed its cycle, switch 23 is activated to contact electrical contact 29 thereby activating an indication light 30 that indicates the test is complete and opens the circuit to the cell 4 thereby stopping supply of electrical current thereto.

Referring to P16. 3, the timer 22 has clutch 22a which activates or deactivates timer 22 and activates switch 23 to contacts 29 or 29a by being linearly depressed into the timer 22. Switch 23 and contacts 29 and 290 are located within timer 122. Switch 20 is closed by rotating knob 40 counter-clockwise to the on position so that arm 59 depresses switch 20. Any suitable timer may be employed. However, it is preferred to employ a timer which when deactivated also is automatically put into a timed out or zero condition so that when subsequent tests are made, initiation of a full cycle is assured. A suitable tiger that can be employed is manufactured by Industrial Timer Corporation of Parsippany, New Jersey and identified as series LVR push button integral timer disclosed in the corporationss bulletin No. 405. The timer 22 is attached to plate by any convenient means so that clutch 22a extends through opening 36. Plate 35 also is provided with four posts 37 which function to prevent accidental depression of the clutch 22a in a manner more fully described hereinafter. Plate 35 also has posts 38 and 39 which function as stop means to limit the degree of rotation of knob 40.

The knob 40 has a generally cylindrical section 42, the inside portion 43 being hollowed out to accommodate clutch 220 which extends therein. Clutch 22a is activated by being contacted with surface 44. The

distance between the surface 44 and clutch 22a is regulated so that clutch 22a is depressed during one rotational cycle of the knob 40. This can be effected by any convenient means as by molding the surface 44 to the desired distance or providing a set screw which extends through hole 45 thereby providing a convenient means for adjusting the linear distance the knob 40 must travel to actuate the clutch 22a. The inside surface 43 of knob 40 is provided with a race 46 into which posts 37 register so that the posts 37 can regulate the linear distance clutch 22a and can be depressed. Cam surface 48 on knob 40 provides the means for converting the rotation of knob 40 into linear motion. The cam surface 48 comprises a series of generally triangular sections having an apex 49 and two oppositely inclined surfaces 50 extending from the apex 49. Each triangular section contacts a prong 51 (See FIG. 6) depending from the inside surface 52 of hood section 1. When the apices 49 contact the prongs 51, the knob 40 is in a linear position closest to the timer 22 and the clutch 22a is in its most depressed condition. When the prongs 51 contact the bottom of the inclined surfaces 50, the knob 40 is in a position furthest from the timer. The clutch 22a is spring-loaded so that it tends to force knob 40 away from timer 22. However, the force generated by contact of the cam surface 48 and the prong 51 overcomes the force of the switch 20. The cylindrical portion 42 of knob 40 extends through the opening 54 of hood 1 and cover 55 is placed thereon.

Cover 55 is provided with a plate 56 which serves as a pointer and has at least one key that fits into a slot 57 so that there is no relative movement between knob 40 and cover 55. Knob 40 is also provided with an arm 59 which actuates a locking mechanism as will be described hereinafter. The race 46 also is shaped with triangular portions have apices 49a which correspond to the apices 49 and inclined surfaces 50a which correspond to the inclined surfaces 50. The posts 37 and prongs 51 are positioned so that they are at the same position of the inclined surfaces or apices for a given rotational position of the knob 40. Referring to FIGS. 1, 7 and 3, the distance that knob 40 can be rotated is determined by means of stops 38 and 39 which contact arm 59 when knob 40 is rotated. In addition, when knob 40 is rotated, extension 60 on arm 59 registers in slot 61 of circular member 62. Circular member 62 has an extension 63 which is adapted to fit into the depression 64 of spring 65. The spring 64 also limits the degree of rotation of member 62. Arm 66 is attached to member 62 and extension 67 is attached to arm 66 so that they rotate with member 62. Extension 67 fits into slot 5 of tray 4 when knob 40 is returned to the start position. Thus, byrotating knob 40 to the start position, the clutch 22a is depressed, currentis supplied to electrodes 11 and 12, tray 4 is locked into position into contact with electrodes 11 and 12 and the knob is in a position to prevent accidental stopping and restarting of the timer. When the test is complete, the test complete light is turned on and the knob 40 is rotated clockwise to the load-unload position to unlock the tray 4 apparatus and put the timer into the zero posinon.

Thus, it will be seen that the invention described above provides, among other features, actuating apparatus having a first member, a second member and a third member and which correspond respectively to the illustrated knob 40, the hood section 1, and the plate 35. The first member is mounted with the second and third members for rotation relativeto them about an axis and for translation relative to them along this rotation axis, and has first and second surfaces thereon facing opposite directions along the axis. These surfaces correspond respectively to the cam surface 48 and the race 46 in the illustrated embodiment. Further, the actuating apparatus has a third surface, corresponding to the inside surface 52 of the illustrated embodiment, on the second member and facing toward and slidably engaged with the aforementioned first surface during the relative rotation of the first member, and this third surface is paired with the first surface. The actuating apparatus also includes a fourth surface on the third member and which faces toward and is slidably engaged with the aforementioned second surface during the relative rotation of the first member. This forth surface, which is paired with the third surface, is formed in the illustrated embodiment described above by the posts 37. Further in accordance with the invention, two of these four surfaces, one in each pair thereof, are undulated in the direction of the rotation axis with uniformly-spaced undulation peaks and undulation trough. The other two of these surfaces, also one in each pair thereof, comprise at least three undulationengaging protrusions which extend toward and slidably engage the surface paired therewith. These other surfaces are rotatably positioned to engage locations on the respective undulated surfaces paired therewith which are complementary to each other. This means that one such older surface engages an undulation peak when the remaining other surface engages an undulation trough. Also in accordance with the invention, this actuating apparatus has means which maintain the socalled other surfaces spaced apart by a fixed distance along the axis of rotation. In addition, the first member of this actuating apparatus has a torque-receiving portion for imparting the aforementioned relative rotation to it, and it has the aforementioned first and second surfaces on it formed along circular paths which are centered on the rotation axis. Moreover, the first member has a bearing surface facing along the rotation axis. Again with referenceto the illustrated embodiment, this bearing surface is the surface 44 on the knob 40.

The cam and prongs need not be limited to the arrangement shown in the drawings to attain the desired linear displacement of the timer clutch. For example, both sets of prongs canbe located on the flanged portion of the rotatable knob to register'with cam surfaces on the inside of the hood and the plate attached to the timer. However, it is preferred that the cam surfaces be located on the rotatable member since they can be molded simultaneously. Furthermore, is not necessary that each pair of oppositely inclined surfaces on the cams connect to the next adjacent pair of inclined surfaces. A flat surface can be interposed between each pair of oppositely inclined surfaces if desired. When employed in combination with a timed power supply it is only necessary that stop means be provided so that only one recipricating cycle is effected for each rotational cycle.

When the control apparatus shown is employed in conjunction with a timed power supply, substantial advantages are attained. Thus, when the power is being supplied or if the test is complete when the control knob is in the test on position, the timer switch cannot be depressed either to stop or restart the test cycle. Furthermore, fail-safe apparatus can be appended to the knob so that the samples being tested are not removed from the source of power prior to completing the test period.

lclaim:

1. Apparatus for converting rotational displacement into linear displacement comprising a rotatable member and two stationary members, at least a portion of each of said stationary members bearing against a surface of said rotatable member to form two pairs of surfaces, each pair consisting of a rotatable surface and a stationary surface, one surface of each pair being a generally circular surface having a plurality of alternating oppositely-inclined surfaces joined together to form a plurality of apexes, thereby defining a circular cam,

and the other surface of each pair being defined by discrete spaced elements each element registering with one pair of the oppositely-inclined surfaces defining said cam to thereby form a plurality of cam-followers each pair of surfaces being arranged so that for a given rotational displacement of said rotatable member the discretely spaced cam-follower elements contact the cam surfaces such that the axial movement induced by each cam-cam-follower combination as a result of rotation of said rotational member is in the same amount and in the same direction and the cam-followers elements of one surface engage a portion of said cam surface-which is complementary to the portion of the corresponding cam surface engaged by the cam-follower elements of the other surface.

2. The apparatus of claim 1 wherein the circular cams are on the rotating member.

3. The apparatus of claim 1 having stop means of said stationary members bearing against a surface of said rotatable member to form two pairs of surfaces, each pairconsisting of a rotatable surface and a stationary surface, one surface of each pair being a generally circular surface having a plurality of alternating oppositely-inclined surfaces joined together to form a plurality of apexes, thereby defining a circular cam,

and the other surface of each pair being defined by discrete spaced elements each element registering with one pair of the oppositely-inclined surfaces defining said cam to thereby form a plurality of cam-followers each pair of surfaces being arranged so that for a given rotational displacement of said rotatable member the discretely spaced cam-follower elements contact the cam surfaces such that the axial movement induced by each cam-cam-follower combination as a result of rotation of said rotational member is in the same amount and in the same direction and the cam-fllowers elements of one surface engage a portion of said cam surface which is complementary to the portion of the corresponding cam surface engaged by the cam-follower elements of the other surface.

5. The apparatus of claim 4 wherein the circular cams are on the rotating member.

6. The apparatus of claim 4 having stop means adapted to contact said rotating member to regulate rotational displacement.

7. The apparatus of claim 4 having a projection attached to and extending radially from said rotatable member, said projection adapted to actuate means for retaining a tray containing test samples in contact with said electrical contacts.

8. The apparatus of claim 7 wherein the circular cams are on said rotatable member.

9. Actuating apparatus comprising a first member a second member a third member said first member being mounted with said second and third members for rotation relative thereto about an axis and for translation relative thereto along said axis,

first and second surfaces on said first member facing in opposite directions along said axis,

a third surface on said second member facing toward and slidably engaged with said first surface during said relative rotation and being paired therewith,

a fourth surface on said third member facing toward slidably engaged with said second surface during said relative rotation and being paired therewith,

two of said surfaces, one in each pair thereof, being undulated in the direction of said axis with at least three uniformly spaced undulation peaks and undulation troughs,

the other surfaces, one in each pair thereof, comprising at least three undulation-following protrusions extending toward and slidably engaged with the surface paired therewith, and

comprising means maintaining said other surfaces spaced apart by a fixed distance along said axis.

11. Actuating apparatus as defined in claim 10 in which said first member has a torque-receiving portion for imparting said relative rotation to it, and

has said first and second surfaces. thereof formed along circular paths centered on 'said axis.

l2. Actuating apparatus as defined in claim 11 in which said first member further comprises a bearing surface facing along said axis, 

1. Apparatus for converting rotational displacement into linear displacement comprising a rotatable member and two stationary members, at least a portion of each of said stationary members bearing against a surface of said rotatable member to form two pairs of surfaces, each pair consisting of a rotatable surface and a stationary surface, one surface of each pair being a generally circular surface having a plurality of alternating oppositely-inclined surfaces joined together to form a plurality of apexes, thereby defining a circular cam, and the other surface of each pair being defined by discrete spaced elements each element registering with one pair of the oppositely-inclined surfaces defining said cam to thereby form a plurality of camfollowers each pair of surfaces being arranged so that for a given rotational displacement of said rotatable member the discretely spaced cam-follower elements contact the cam surfaces such that the axial movement induced by each cam-cam-follower combination as a result of rotation of said rotational member is in the same amount and in the same direction and the camfollower''s elements of one surface engage a portion of said cam surface which is complementary to the portion of the corresponding cam surface engaged by the cam-follower elements of the other surface.
 2. The apparatus of claim 1 wherein the circular cams are on the rotating member.
 3. The apparatus of claim 1 having stop means adapted to contact said rotating member to regulate rotational displacement.
 4. Apparatus for supplying electrical power comprising an electrical power source, a timer, switch means to initate a timed cycle of said timer and to supply power from said power source to a set of electrical contacts and means for actuating said switch means comprising apparatus for converting rotational displacement into linear displacement comprising a rotatable member and two stationary members, at least a portion of each of said stationary members bearing against a surface of said rotatable member to form two pAirs of surfaces, each pair consisting of a rotatable surface and a stationary surface, one surface of each pair being a generally circular surface having a plurality of alternating oppositely-inclined surfaces joined together to form a plurality of apexes, thereby defining a circular cam, and the other surface of each pair being defined by discrete spaced elements each element registering with one pair of the oppositely-inclined surfaces defining said cam to thereby form a plurality of cam-followers each pair of surfaces being arranged so that for a given rotational displacement of said rotatable member the discretely spaced cam-follower elements contact the cam surfaces such that the axial movement induced by each cam-cam-follower combination as a result of rotation of said rotational member is in the same amount and in the same direction and the cam-follower''s elements of one surface engage a portion of said cam surface which is complementary to the portion of the corresponding cam surface engaged by the cam-follower elements of the other surface.
 5. The apparatus of claim 4 wherein the circular cams are on the rotating member.
 6. The apparatus of claim 4 having stop means adapted to contact said rotating member to regulate rotational displacement.
 7. The apparatus of claim 4 having a projection attached to and extending radially from said rotatable member, said projection adapted to actuate means for retaining a tray containing test samples in contact with said electrical contacts.
 8. The apparatus of claim 7 wherein the circular cams are on said rotatable member.
 9. Actuating apparatus comprising a first member a second member a third member said first member being mounted with said second and third members for rotation relative thereto about an axis and for translation relative thereto along said axis, first and second surfaces on said first member facing in opposite directions along said axis, a third surface on said second member facing toward and slidably engaged with said first surface during said relative rotation and being paired therewith, a fourth surface on said third member facing toward and slidably engaged with said second surface during said relative rotation and being paired therewith, two of said surfaces, one in each pair thereof, being undulated in the direction of said axis with at least three uniformly spaced undulation peaks and undulation troughs, the other surfaces, one in each pair thereof, comprising at least three undulation-following protrusions extending toward and slidably engaged with the surface paired therewith, and said other surfaces being rotationally positioned, relative to the undulated surfaces paired therewith, to engage locations on the respective undulated surfaces paired therewith which are complementary to each other, so that one other surface engages an undulation peak when the remaining other surface engages an undulation trough.
 10. Actuating apparatus as defined in claim 9 further comprising means maintaining said other surfaces spaced apart by a fixed distance along said axis.
 11. Actuating apparatus as defined in claim 10 in which said first member has a torque-receiving portion for imparting said relative rotation to it, and has said first and second surfaces thereof formed along circular paths centered on said axis.
 12. Actuating apparatus as defined in claim 11 in which said first member further comprises a bearing surface facing along said axis. 